为什么的BinaryWriter prePEND胡言乱语到流的开始？你如何避免呢？ [英] Why does BinaryWriter prepend gibberish to the start of a stream? How do you avoid it?

问题描述

我调试与写作部分的目的是文件的一些问题，我已经得到了下来，只是打开文件，并在其写入TEST的基本情况。我被像这样：

 静态的FileStream FS;
静态的BinaryWriter瓦;
FS =新的FileStream（文件名，FileMode.Create）;
W =新的BinaryWriter（FS）;

w.Write（测试）;

w.Close（）;
fs.Close（）;
 

不幸的是，这结束了prepending一个框，该文件的前面，它看起来像这样：

测试，与前面一个有趣的盒子。这是为什么，我怎么能避免呢？

编辑：这似乎没有在这里显示框，但它看起来像乱码的UNI code字

。

解决方案

他们没有字节顺序标记，但一个长度 - preFIX，根据的 MSDN ：

 公共虚拟无效写入（字符串值）;
 

  

写入pfixed字符串到长度 - $ P $   [中]流

和你需要的长度 - preFIX如果你想读的字符串，从该点回来。请参阅<一href="http://msdn.microsoft.com/en-us/library/system.io.binaryreader.readstring.aspx"><$c$c>BinaryReader.ReadString().

其他

因为它似乎你真正想要一个文件头检查

1. 这是个问题吗？你读的长度 - preFIX回来，为的文件类型，检查它的工作原理确定

2. 您可以将字符串转换为一个byte []数组，可能使用Encoding.ASCII。但母鸡，你必须要么使用一个固定的（隐含的）长度或... preFIX它自己。看完字节[]可以再次将其转换为字符串。

3. 如果你有大量的文字来写你甚至可以附加的TextWriter以相同的流。但要小心，作家要关闭其流。我不会劝告这个情况的，但它是很好的了解。这里也你必须标记一个点，其他的读者可以接管（固定头工程确定）。

I'm debugging some issues with writing pieces of an object to a file and I've gotten down to the base case of just opening the file and writing "TEST" in it. I'm doing this by something like:

static FileStream fs;
static BinaryWriter w;
fs = new FileStream(filename, FileMode.Create);
w = new BinaryWriter(fs);

w.Write("test");

w.Close();
fs.Close();

Unfortunately, this ends up prepending a box to the front of the file and it looks like so:

TEST, with a fun box on the front. Why is this, and how can I avoid it?

Edit: It does not seem to be displaying the box here, but it's the unicode character that looks like gibberish.

解决方案

They are not byte-order marks but a length-prefix, according to MSDN:

public virtual void Write(string value);

Writes a length-prefixed string to [the] stream

And you will need that length-prefix if you ever want to read the string back from that point. See BinaryReader.ReadString().

Additional

Since it seems you actually want a File-Header checker

1. Is it a problem? You read the length-prefix back so as a type-check on the File it works OK

2. You can convert the string to a byte[] array, probably using Encoding.ASCII. But hen you have to either use a fixed (implied) length or... prefix it yourself. After reading the byte[] you can convert it to a string again.

3. If you had a lot of text to write you could even attach a TextWriter to the same stream. But be careful, the Writers want to close their streams. I wouldn't advice this in general, but it is good to know. Here too you will have to mark a Point where the other reader can take over (fixed header works OK).

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